47908

Appears in sequences

• Number of segments (and sides) created by diagonals of an n-gon in general position.at n=26A014628
• A unitary phi reciprocal amicable number: consider two different numbers r, s which satisfy the following equation for some integer k: uphi(r) = uphi(s) = (1/k) * r * s / (r-s); or equivalently, 1/uphi(r) = 1/uphi(s) = k * (1/s - 1/r); sequence gives r numbers.at n=15A080766
• Numbers which when multiplied by any repunit prime Rp give a Smith number.at n=29A104167
• Numbers k such that k^2 divides 15^k-1.at n=30A128395
• Row sums of triangle A134392.at n=27A134393
• Number of line segments in regular n-gon with all diagonals drawn.at n=28A135565
• a(n) = n*(2*n^2 + 5*n + 3).at n=28A163815
• 15-gonal (or pentadecagonal) pyramidal numbers: a(n) = n*(n+1)*(13*n-10)/6.at n=28A177890
• a(n) = Sum_{0 < x,y,z <= n and gcd(x^2 + y^2 + z^2, n)=1} gcd(x^2 + y^2 + z^2 - 1, n).at n=28A239612
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 563", based on the 5-celled von Neumann neighborhood.at n=35A272941
• Number of 4-cycles in the n X n black bishop graph.at n=16A289162
• Numbers k such that all digits in k are different and for each digit d it is true that k = d (mod sum of digits(k) - d).at n=25A306788
• a(n) = Sum_{k=0..n} binomial(n+2*k+2,n-k) * Fibonacci(k+1).at n=8A390827